Where can I find directions on loading the front Paper Feed Slot?

It is in the HTML manual. Try clicking links in this order:

1. Basic Operation and Instructions
2. Loading paper for printing
3. Steps to Load Sheets in the Paper Tray
4. Follow the listed steps 1-4 on that page
5. Click on "Put Sheets in the Tray"
6. Click on the link in this text: "However, if you have specified POP Board, insert the sheet in the Paper Feed Slot."